Hard alloy with exceedingly good comprehensive properties is used for making cutting tool, mould, drilling tools, and other wear-resistant and shock resistant parts for machinery, electronics, chemical industry, petroleum, geological prospecting, etc. Rare earth metals containing hard alloys are tough, oxidation resistant, shock resistant, and strong under high temperature.
A good deal of attention has been paid to the development of this material. The rare earth containing hard alloy is conventionally prepared by powder metallurgy, in which the powders of raw materials are mixed and milled according to a required composition, followed by drying, shaping by pressing, and sintering to produce hard alloy having a required shape. DE 3,228,692, Japan Patent Application 59-43,840,61-183,429, and China Patent Application CN 89,105,708 disclosed several processes for preparing rare earth containing hard alloy, in which the powder of rare earth metals, the powder of rare earth oxides and the powder of nitride were used as raw materials and were mixed directly with the powders of carbides and other materials to make rare earth metal containing hard alloy. The property of the rare earth metal containing hard alloy thus prepared was improved to a certain extent as compared to the hard alloy without rare earth metals. However, the disadvantages of the prior art are as follows. First instability of the alloy property. The incorporation of the rare earth metals by above mentioned processes applies more strict demands to the technology of alloy preparation. The rare earth metals may exist in the alloy in a state of bulky rare earth phase such as lump, pieces with multiangles, etc. The bulky rare earth metal phase occludes with the alloy, which diminishes the effect of the rare earth and causes the instability of the product. Second, the preparation of different alloy series with different composition (including mainly WC--Co, WC--TiC--Co, and WC--TiC--TaC--(NbC)--Co series) and the quantity of the rare earth metals incorporated into the hard alloy, all require the optimization of the parameters in preparation procedure of such alloys. Hence, the preparation technology becomes too complicated to commercialize. The above listed disadvantages limit the production and application of rare earth containing hard alloy in a wider range.